A headphone set includes receivers, a signal processor that applies a given processing to each of audio signals received by respective ones of the receivers, a first adder that adds left signals together, to which the given processing is applied, a second adder that adds right signals together, to which the given processing is applied, a first sound output device that outputs a sound based on an output signal of the first adder, and a second sound output device that outputs a sound based on an output signal of the second adder.